Opening with a newsreel that captures the global anticipation for Santa, the story follows Special Delivery 'S.D.' Kluger, Fred Astaire, a cheerful yet weary postman whose truck breaks down while trying to deliver letters to Santa. Rather than give up, he uses the moment to tell the tale of Santa in response to the heartfelt letters from children.
In Sombertown, a baby named Claus arrives on the doorstep of the gruff Mayor Burgermeister Meisterburger, [Paul Frees], who orders Grimsley to take the infant to an orphanage. A sudden gust of wind swoops the baby away, setting off a sequence of events that will shape his destiny. Aided by a loyal band of animals, the infant is carried to the Kringles, a generous family of elves who name him Kris, Mickey Rooney (the voice), and raise him with care, teaching him how to craft toys and live as part of a family whose trade is joy.
When Kris reaches adulthood, he volunteers to travel to Sombertown to bring gifts to children. Along the journey, he befriends a lost penguin who becomes his companion, Topper. Back in town, trouble arises after Meisterburger, who has tripped over a toy duck, issues a sweeping ban on all toys. Kris arrives bearing gifts for the children and even gives one to Miss Jessica, Robie Lester, the town’s kind schoolteacher. The Mayor orders Kris’s arrest, forcing Kris to flee into the forest with Topper. They are soon captured by the Winter Warlock, Keenan Wynn, who is initially wary but grows to trust Kris after he is given a toy train that rekindles a spark of warmth in him.
To prevent further toy distribution, Meisterburger locks every door and window, but Kris manages to slip in through chimneys and place toys in the children’s stockings. The Mayor devises a cruel trap, and Winter along with the Kringles are captured. Jessica visits Winter in prison, where he reveals that most of his magic has faded except for enchanted corn that allows some of Kris’s reindeer friends to fly. With the help of these reindeer, Kris and his companions stage a daring escape.
Kris returns to town wearing a beard as a disguise and reclaims his Claus identity. He marries Jessica, and together they travel to the North Pole to establish a toy workshop that will become the foundation of Santa’s operation. In time, Meisterburger’s anger fades and his legacy is erased, and Claus is canonized as Saint Nicholas, the legend of Santa Claus. As a thoughtful rule grows from his mission, Santa limits his gift-giving to Christmas Eve, honoring the anniversary of his wedding to Jessica.
After the tale is finished, S.D. Kluger realizes there are still letters to deliver to Santa. He heads out in his now-repaired truck, joined by Topper, Winter, and a procession of joyful children, all singing the familiar tune, “Santa Claus Is Coming to Town,” as they roll toward the unknown and the magic of the season.
